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Denver, South Park and Pacific Railroad
DSP&P Mason Bogie 2-6-6T Locomotives

The Mason Machine Works was founded in 1842 by William Mason of Taunton, MA.-Mason built stationary engines, locomotives, and cotton machinery. Mason's innovative locomotive designs quickly drew praise from railroad engineers and operators, and were known to be the easiest engines to repair. The company constructed 754 steam locomotives between 1853 and 1889. However, after Mason's death in 1883, the firm concentrated on its core business of textile machinery.

Although his plant produced many well known conventional locomotives, he is often better known for his adaptation of the Fairlie style articulated locomotive, which became known as the Mason Bogie, or Double-Truck locomotive. His design placed the driving wheels on an articulated frame under the boiler that allowed it to swivel, which provided better tracking on on sharp curves and rough roadbed. The fuel and water tender was on the engines main frame, carried by a six-wheel truck. The South Park purchased 23 of the 147 Bogie locomotives built by Mason. The Forney locomotive looked similar but most Forney's were not articulated. 

This page covers the DSP&P 2-6-6T Mason Bogies. They also owned four of the 2-8-6T model.

DSP&P RR LOCOMOTIVES   1874 - 1899 

3 Oro City 40 2-6-6T Mason 1878
4 San Juan 41 2-6-6T Mason 1878
5 Leadville 291 2-6-6T Mason 1878
6 Tenmile 42 2-6-6T Mason 1879
7 Gunnison 43 2-6-6T Mason 1879
8 Lake City 44 2-6-6T Mason 1879
9 Kenosha 50 2-6-6T Mason 1879
10 Granite 45 2-6-6T Mason 1879
11 Ouray 46 2-6-6T Mason 1879
12 Como 47 2-6-6T Mason 1879
13 Ruby 48 2-6-6T Mason 1879
14 Twin Lakes 58 2-6-6T Mason 1879
15 Breckenridge 51 2-6-6T Mason 1879
16 Eureka 52 2-6-6T Mason 1879
20 Silverton 53 2-6-6T Mason 1879
21 Pitkin City 54 2-6-6T Mason 1879
22 Crested Butte 55 2-6-6T Mason 1880
23 Grant 56 2-6-6T Mason 1880
24 Buena Vista 57, C&S 1 2-6-6T Mason 1880

DSP&P #3 "Oro City" and # 4 "San Juan" were the first two Mason Bogies delivered in 1878. DSP&P #5 "Leadville" started life on the Kansas Central. She rolled over into a ravine and was sent back to Mason as "unsatisfactory". Mason rebuilt the engine and it was added to the DSP&P roster in late 1878. She was lighter than #3 and #4, and had smaller drivers -- 34" instead of 37". In the UP renumbering of 1885, she received #291 in the "odd-ball" series instead of the 40 through 60 series reserved for the other Bogies.

DSP&P Bogies #6 through #16 weighed in at 37 tons with 42" boiler diameter, arriving in 1879. Nearly all of these Mason locomotives were gone by 1890, replaced by more modern 2-6-0 and 2-8-0 locomotives.

DSP&P #20 and #21 arrived in 1879 and had considerably larger cylinders than previous models. These two lasted until 1894 and spent their later years on the Utah and Northern.

The last three 2-6-6T Bogies, DSP&P #22, #23, #24, were similar to the DSP&P #6 through #16 series. Only #24 made it into the C&S roster in 1899 (C&S #1). It was sold in 1902 and ended up in Ames Iowa on display. Weather and vandalism pretty well destroyed its original engineering beauty and it was given to a World War Two scrap drive. The only remaining Mason Bogie is the (non-DSP&P) "Torch Lake" at Greenfield Village in Dearborn Michigan.

Below are the four Mason Bogies on the author's large scale model railway.

The (fictitious) DSP&P 0-4-4T Mason Bogie #3 "South Park"           DSP&P #15 "Breckenridge"                   

DSP&P #4 "San Juan" and
#6 "Tenmile"  (Accucraft Builder's Photo)

See also CAD Drawings

DSP&P #4 "San Juan" Builder's Photo

DSP&P #10 "Granite" in Action

DSP&P #13 "Ruby"

Builder's Photo, taken in 1879, of DSP&P 2-6-6T Mason Bogie #15 "Breckenridge". The lettering was probably gold with red drop-shadow. The boiler was russia iron, probably light grey or blue, cab and tender box probably dark green or brown, brightwork polished brass. Photos could not be reproduced in magazines or newspapers until after 1890 when the duotone process was invented, so engravers were assigned to redraw photos, as shon below in the "Folios and Plans" section.

DSP&P #22 "Crested Butte"

DSP&P #6 "Tenmile" after being renumbered to #42

DSP&P #7 "Gunnison" after being renumbered to #43

DSP&P #8 "Lake City" after being renumbered to #44

DSP&P #11 "Ouray" after being renumbered to #46

DSP&P #22 "Crested Butte" after being renumbered to #55

DSP&P #24 "Buena Vista" after being renumbered to #57

See also CAD Drawings

A 7 sheet set of 2-6-6T plans by Art Wallace are available from the Denver, South Park and Pacific Historical Society www.dspphs.org  dspphs@gmail.com  at a scale of 1.5" = 1', 1" = 1', or 0.5" = 1'.

David Fletcher's CAD drawings of "San Juan" appeared in the April 2009 issue of Narrow Gauge Downunder, Dave's plans and CAD imaes inspired the Accucraft 1:20.3 models. Click HERE for full size image.

Below are the Mason Locomotive Works builder's photo, the Railway Age engraving,  and Evelyn Curro's wonderful art print of the well known DSP&P 2-6-6T Mason Bogie #15 "Breckenridge".



Engraving of DSP&P 2-6-6T Mason Bogie #15 "Breckenridge", originally published in "Railway Gazette" in 1879, reprinted in "Recent Locomotives" by Mathias Forney in 1886, and again in "Early American Locomotives" by John White Jr in 1972. Drawn from the builder's photo.  Click on image to capture larger image (0.75 Mb)

This folio is for C&S #1, the only DSP&P Mason Bogie to last this long.

 Here is John Maxwell's plan for DSP&P Mason Bogies.

DSP&P 2-6-6T  Mason Bogie #15 "Breckenridge" and Others


DSP&P 2-6-6T Mason Bogie -- General Laayout

DSP&P 2-6-6T Mason Bogie #14 "Twin Lakes"

DSP&P 2-6-6T Mason Bogie #3 "Oro City"

DSP&P 2-6-6T Mason Bogie #6 "Tenmile"

DSP&P 2-6-6T Mason Bogie #15 "Breckenridge" Page 1

DSP&P 2-6-6T Mason Bogie #15 "Breckenridge" Page 2

DSP&P 2-6-6T Mason Bogie #6 "Tenmile"

DSP&P 2-6-6T Mason Bogie #8 "Lake City"
shown after 1885 as DSP&P #44

DSP&P 2-6-6T Mason Bogie Variations

DSP&P Mason Bogie #3 and #4, "As Delivered" 1878, short tender, wood cab, arched windows, diamond stack

DSP&P Mason Bogie #3, #4, and #6, 1879, short tender, wood cab, arched windows, Nesmith stack

DSP&P Mason Bogie #3, #4, and #6, 1883 - 1885, short tender, metal cab, rectangular windows, Congdon stack, air tank on rear tender deck

DSP&P Mason Bogie #8, 1883 - 1885, short tender, metal cab, rectangular windows, Congdon stack, air tank on top of tender, large headlight

Copyright 2022  E. R. (Ross) Crain, P.Eng.  email